The present invention relates to a reader and/or writer apparatus, a power feeding system and a communication system for performing power feeding for proximate wireless operation and communication between, for instance, a cash dispenser, electronic money, an automatic ticket checking system, a room entrance/exit management system or a pay telephone and a proximate wireless card, such as a cash card, a credit card, a passenger ticket, a commuting ticket, a coupon ticket, a control card, an IC card, a license or a telephone calling card.
It is already known that, by using light or a magnetic field, electric power can be supplied in a non-contact manner from the power feeding side to a proximate wireless card (IC card).
For example, Japanese Patent No. 2626882 (JP-A-8-263609) discloses a technique related to disposing a metal plate on a back of a coil-shaped antenna to prevent wrong operation such as reading card data from a back of a non-contact card reader, especially a technique for adjusting a distance between the metal plate and the coil-shaped antenna in consideration of the fact that the resonant frequency shifts when the metal plate is disposed.
In non-contact card systems (proximate wireless card systems), cash cards, credit cards, passenger tickets, commuting tickets and the like for use at the gates of railway stations, on buses and exit/entrances are made as IC cards. When the user of such an IC card causes the IC card to pass in a non-contact manner through a reader/writer provided at the gate of a railway station, on a bus or at an exit/entrance, a power feeding wave or a communication wave is radiated from a coil or an antenna of the reader and/or writer, this electromagnetic wave is received and induced by a coil or an antenna on the card side to actuate a circuit on the card side and to detect a signal. In this case, an electric field radiated from the coil or antenna of the reader and/or writer should satisfy the requirement of the Wireless Telegraphy Act (500 .mu.V/m at a distance of 3 m from the reader and/or writer).
However, there is involved the problem that, as the aforementioned requirement of the Wireless Telegraphy Act (500 .mu.V/m at a distance of 3 m from the reader and/or writer) regarding the radiated electric field determines the upper limit of the amperage of the coil or antenna for the reader and/or writer and hence the upper limit of power feeding, it is difficult to feed sufficient power to the IC card. That is, there is involved the problem that sufficient power feeding from the reader and/or writer to the IC card at a desired distance from the reader and/or writer and suppression of a far field prescribed in the Wireless Telegraphy Act is difficult.